15794 Make "related objects" dynamic (#15876)

* Closes #15794: Make "related objects" dynamic

Instead of hardcoding relationships between models for the detail view,
they are now dynamically generated.

* Fix related models call

* Remove extra related models hook

Instead of providing a rarely used hook method, additional related
models can now be passed directly to the lookup method.

* Fix relations view for ASNs

ASNs have ManyToMany relationships and therefore can't used automatic
resolving. Explicit relations have been restored as before.

* Add method call keywords for clarification

* Cleanup related models

---------

Co-authored-by: Jeremy Stretch <jstretch@netboxlabs.com>

netbox/core/views.py

@@ -32,7 +32,7 @@ from netbox.views.generic.mixins import TableMixin
 from utilities.forms import ConfirmationForm
 from utilities.htmx import htmx_partial
 from utilities.query import count_related
-from utilities.views import ContentTypePermissionRequiredMixin, register_model_view
+from utilities.views import ContentTypePermissionRequiredMixin, GetRelatedModelsMixin, register_model_view
 from . import filtersets, forms, tables
 from .models import *
 
@@ -51,16 +51,12 @@ class DataSourceListView(generic.ObjectListView):
 
 
 @register_model_view(DataSource)
-class DataSourceView(generic.ObjectView):
+class DataSourceView(GetRelatedModelsMixin, generic.ObjectView):
     queryset = DataSource.objects.all()
 
     def get_extra_context(self, request, instance):
-        related_models = (
-            (DataFile.objects.restrict(request.user, 'view').filter(source=instance), 'source_id'),
-        )
-
         return {
-            'related_models': related_models,
+            'related_models': self.get_related_models(request, instance),
         }